Last week the game Toki no Kizuna was released in Japan.
The era is Sengoku Period. It’s been a little over a year since the death of Toyotomi Hideyoshi and a time when the history of the people is moving greatly once more…. The Oni got swallowed by that wave and made their move too. Oni are clans that live in the shadows of history; the backstage of the world.
Among the ten clans, the heroine is the leader of the Suzumori clan. She is a guard for Yase-hime, the head of these ten clans. Anxious about the involvement into the fight of humans, Yase-hime decided to gather together the clan leaders who are scattered across the land, in order to tell them to break away from human contact. On the night the demons followed through with her orders, Yase-hime was attacked and fell into a deep sleep. The ten clan leaders started to search for the attacker, which means clearly coming into contact with humans. On one hand, Yukina has two missions to carry out—-“Search for a way to revive the sleeping hime” and “Stop the demons’ involvement in the human society.”
Shouldering a burden by herself, she departs her hometown.
Now, why is this related to Hakuoki? There is plenty of evidence (and the game itself has confirmed it now that it is out) to know that this is set in Hakuoki universe and what happens in Toki no Kizuna influenced in Hakuoki's demons.
1. SPOILERS OF SAITO ROUTE
Amagiri told Saito and Chizuru that the onis used to have great power and were united until the battle of Sekigahara, where the Yukimura clan supported one side and the Kazama another. Not going into any details to not spoil a lot but anyway if you played Saitou route you know this conversation, Toki no Kizuna is about the battle of Sekigahara
2. One of the villains is called Nagumo Shuu, Nagumo is the clan which adopted Chizuru's brother
3. Kazama addressed Senhime as "Yase no Hime" in-game (also mentioned in official settings). In anime Sekkaroku episode 3, around 08:50, Kazama called her "Yase no furuki onna oni", literally "ancient female Oni of Yase".
The background of Toki no Kizuna is Battle of Sekigahara, which took place 264 years before Hakuoki. Therefore Yase-hime could be Senhime's grandma or great-grandma.
4. SPOILERS REGARDING A CHARACTER OF TOKI NO KIZUNA
One of the main characters who can have romance with the heroine is a young man called Kazuya (the one who looks like Saitou). His full name is Chitose Yukimura. Yes, Yukimura.